Anti-seepage structure based on permanent and temporary combined dispersive earth dam

Abstract

The utility model relates to an anti-seepage structure based on a permanent and temporary combined dispersive earth dam. The anti-seepage structure at least comprises a dam foundation. The dispersive earth dam body is formed by filling dispersive earth on a dam foundation; the water retaining cofferdam is arranged on the upstream side of the dispersive earth dam body; the anti-seepage curtain is formed by grouting along the dam axis of the dam foundation; and the drainage impermeable layer is laid on the upstream face of the dispersive earth dam body, the downstream face of the water retaining cofferdam and the space between the dispersive earth dam body and the upstream interlayer of the dam axis of the dam foundation. The geomembranes are sequentially arranged in the directions of the upstream face of the dam, the downstream face of the cofferdam and the dam foundation, the geomembranes are in grouting connection with the curtain at the axis position of the bottom dam of the dam foundation, the geotechnical drainage layers are arranged on the downstream portions of the geomembranes, and the protection layers are arranged on the upstream portions of the geomembranes, so that an anti-seepage drainage system is improved, and deformation coordination with surrounding soil bodies is achieved; in addition, the anti-seepage curtain is arranged at the position of the dam axis at the bottom of the dam foundation, the axis of the anti-seepage curtain can be obviously shortened, and the curtain project amount is reduced.

Description

Technical Field

[0001] The utility model belongs to the field of water conservancy and hydropower engineering construction, and specifically relates to an anti-seepage structure based on a permanent and temporary combined dispersed earth dam. Background Art

[0002] A permanent and temporary combined earth-rock dam refers to a temporary water retaining cofferdam as a part of the permanent dam structure. It can reduce the amount of earth and stone filling and improve the progress of dam construction. It is widely used in different earth-rock dam projects.

[0003] Since dispersed clay is easily eroded by water, it is very important to isolate and protect dispersed soil when building a permanent and temporary combined earth-rock dam in dispersed soil areas. The traditional solution is generally to build an anti-seepage wall inside the cofferdam, set a geomembrane on the dam slope and connect it to the anti-seepage wall, and perform curtain grouting on the bottom plate of the anti-seepage wall. However, the anti-seepage wall is generally rigid, uneven with the surrounding soil, and has a large settlement. At the same time, the curtain grouting axis is not on the dam axis, and the curtain axis length is large, resulting in a large amount of engineering work, and the engineering investment of the anti-seepage wall is generally large. Utility Model Content

[0004] The utility model aims to provide an anti-seepage structure based on a permanent and temporary combined dispersed earth dam to overcome the above technical defects.

[0005] In order to solve the above technical problems, the utility model provides an anti-seepage structure based on a permanent and temporary combined dispersed earth dam, which at least includes:

[0006] Dam foundations;

[0007] The body of a dispersed earth dam is formed by filling dispersed soil on the dam foundation;

[0008] The water retaining cofferdam is arranged on the upstream side of the dispersed earth dam body;

[0009] The anti-seepage curtain is formed by grouting along the dam axis of the dam foundation;

[0010] The drainage and anti-seepage layer is laid on the water-facing surface of the dispersed earth dam body, the back surface of the water retaining cofferdam, and between the dispersed earth dam body and the upstream interlayer of the dam axis of the dam foundation, and the drainage and anti-seepage layer is connected to the anti-seepage curtain;

[0011] The transition layer is set between the drainage and anti-seepage layer and the dispersed earth dam body.

[0012] It is characterized by further comprising:

[0013] Drainage prisms are arranged at the downstream slope foot of the dispersed earth dam body.

[0014] The anti-seepage structure based on permanent and temporary combined dispersed earth dam also includes:

[0015] The supporting layer is arranged upstream of the dam axis and located between the drainage and anti-seepage layer and the dam foundation.

[0016] The drainage and anti-seepage layer includes:

[0017] The geotextile drainage layer is laid in three parts, namely, between the transition layer and the supporting layer, between the transition layer and the backwater surface of the water retaining cofferdam, and between the transition layer and the frontwater surface of the dispersed earth dam body. The joints of the three parts are laid seamlessly.

[0018] The lower composite geomembrane is arranged between the geodrainage layer and the support layer, and between the geodrainage layer and the back surface of the water retaining cofferdam;

[0019] The upper composite geomembrane is arranged on the upstream slope of the geodetic drainage layer.

[0020] The anti-seepage structure based on permanent and temporary combined dispersed earth dam also includes:

[0021] The protective layer is arranged on the upstream slope of the upper composite geomembrane;

[0022] The protective layer consists of a mortar cushion and a concrete slab.

[0023] The anti-seepage structure based on permanent and temporary combined dispersed earth dam also includes:

[0024] The foot-guard wall is arranged on the back side of the water retaining cofferdam and close to the top surface;

[0025] The foot guard wall is embedded in the interior of the water retaining cofferdam.

[0026] The transition layer covers the water-facing surface of the dispersed earth dam body, the backwater surface of the retaining cofferdam, and the dam base of the dam foundation.

[0027] The anti-seepage structure based on permanent and temporary combined dispersed earth dam also includes:

[0028] The lower filter layer is laid downstream of the dam axis of the dam foundation;

[0029] The crushed stone drainage layer is laid on the lower filter layer;

[0030] The upper filter layer is laid on the gravel drainage layer;

[0031] The top surface of the support layer is higher than the top surface of the crushed stone drainage layer, and the crushed stone drainage layer is connected with the geotextile drainage layer.

[0032] The water retaining cofferdam is arranged in steps, including:

[0033] The dike is arranged on the upstream side of the dispersed earth dam body;

[0034] Air-tight material, arranged on the upstream side of the dike;

[0035] Homogeneous soil fill, arranged on the downstream side of the dike;

[0036] The top surfaces of the airtight material, the dike and the homogeneous soil filling material gradually rise and form three steps. Cofferdam slope protection is laid on the top surfaces of the three, and the top surface of the cofferdam slope protection is flush with the top surface of the homogeneous soil filling material.

[0037] The utility model provides an anti-seepage structure based on a permanent and temporary combined dispersed earth dam, which adopts a geomembrane which is arranged in sequence along the water-facing surface of the dam, the back water surface of the cofferdam and the direction of the dam foundation, and the geomembrane is connected to the dam foundation by curtain grouting at the dam axis position, and a geotechnical drainage layer is arranged downstream of the geomembrane, and a protective layer is arranged upstream, so as to improve the anti-seepage drainage system and coordinate with the deformation of the surrounding soil; in addition, the anti-seepage curtain is arranged at the dam axis position at the bottom of the dam foundation, which can significantly shorten the anti-seepage curtain axis and reduce the curtain engineering workload.

[0038] In order to make the above contents of the present invention more clearly understood, preferred embodiments are given below and described in detail in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a cross-sectional diagram of the anti-seepage structure based on the permanent and temporary combined dispersed earth dam.

[0040] Figure 2 It is a cross-sectional view of the water retaining cofferdam.

[0041] Description of reference numerals:

[0042] 1. Dispersed soil filling area;

[0043] 2. Water retaining cofferdam; 2-1. Dike; 2-2. Air-tight material; 2-3. Homogeneous soil filler; 2-4. Cofferdam slope protection;

[0044] 3. Transition layer;

[0045] 4. Geotechnical drainage layer;

[0046] 5-1. Lower composite geomembrane; 5-2. Upper composite geomembrane;

[0047] 6. Protective layer;

[0048] 7. Foot protection tooth wall;

[0049] 8. Anti-seepage curtain;

[0050] 9-1. Gravel drainage layer; 9-2. Lower filter layer; 9-3. Upper filter layer;

[0051] 10. Drainage prism;

[0052] 11. Support layer;

[0053] 12. Dam foundation. DETAILED DESCRIPTION

[0054] The following is an explanation of the implementation of the present invention by means of specific embodiments. Those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification.

[0055] It should be noted that, in the present utility model, the top, bottom, left and right in the figure are deemed to be the top, bottom, left and right of the anti-seepage structure based on the permanent and temporary combined dispersed earth dam described in this specification.

[0056] The exemplary embodiments of the present invention are now introduced with reference to the accompanying drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. These embodiments are provided to disclose the present invention in detail and completely and to fully convey the scope of the present invention to those skilled in the art. The terms in the exemplary embodiments shown in the accompanying drawings are not intended to limit the present invention. In the accompanying drawings, the same units / elements are marked with the same reference numerals.

[0057] Unless otherwise specified, the terms (including technical terms) used herein have the commonly understood meanings to those skilled in the art. In addition, it is understood that the terms defined in commonly used dictionaries should be understood to have the same meanings as those in the context of the relevant fields, and should not be understood as idealized or overly formal meanings.

[0058] This implementation method involves an anti-seepage structure based on a permanent and temporary combined decentralized earth dam. Figure 1 The anti-seepage structure at least includes a dam foundation 12, and a dispersed earth dam body 1 is formed by filling dispersed soil on the dam foundation 12. Figure 1 The figure mark 1 in the figure can also be considered as the dispersed soil filling area, which is the main filling area of ​​the dam project. It is used when there is no non-dispersed soil material near the project area. The soil is mainly taken from the excavated materials in the project area or the nearby area. The compaction degree meets the requirements of the "Design Code for Roller-Compacted Earth-Rock Dams" (SL274-2020).

[0059] A water retaining cofferdam 2 is arranged on the upstream side of the dispersed earth dam body 1, and its function is to guide the flood to the diversion hole or diversion bottom hole, and provide dry land construction conditions for the main dam filling. In order to ensure the overall filling quality of the cofferdam, a step-by-step arrangement is adopted, which consists of a dike 2-1, airtight material 2-2, homogeneous soil filling material 2-3, and cofferdam slope protection 2-4.

[0060] Regarding the structure of water retaining cofferdam 2, please refer to Figure 1 and Figure 2 , which is arranged in steps, including:

[0061] (1) The dike 2-1 is arranged on the upstream side of the dispersed earth dam body 1.

[0062] In the non-flood season, the dike 2-1 can quickly cut off the water flow. The dike 2-1 is a mixture of boulders, pebbles and gravel, and the top surface elevation of the dike 2-1 should be more than 50 cm higher than the normal water level at the inlet of the diversion tunnel to facilitate blocking the normal flow of water.

[0063] (2) The air-tight material 2-2 is arranged on the upstream side of the dike 2-1.

[0064] Air-tight material 2-2 uses non-dispersible soil or modified dispersible soil as the anti-seepage body of the first-order cofferdam to provide dry land construction conditions for the construction of the downstream second-order cofferdam. The air-tight material step position should be 1m lower than the lowest water level upstream of the cofferdam. Among them, the modified dispersible soil uses dispersible soil mixed with 1% to 4% slaked lime, and the specific amount needs to be determined based on field tests.

[0065] (3) Homogeneous soil filler 2-3 is arranged on the downstream side of the dike 2-1.

[0066] Homogeneous soil filler 2-3 uses non-dispersible soil or modified dispersible soil. Modified dispersible soil uses dispersible soil mixed with 1% to 4% slaked lime. The specific amount of mixing needs to be determined based on field tests. The top elevation of homogeneous soil filler 2-3 reaches the design elevation of the cofferdam. Since homogeneous soil filler 2-3 will be part of the permanent structure of the dam in the later stage, it should meet the filling requirements of the main project, and the compaction degree should meet the requirements of the "Design Code for Roller Compacted Earth-Rock Dams" (SL274-2020).

[0067] (4) Cofferdam slope protection 2-4.

[0068] The top surfaces of the airtight material 2-2, the dike 2-1 and the homogeneous soil filling material 2-3 gradually rise and form three steps, on the top surfaces of which the cofferdam slope protection 2-4 is laid, the top surface of the cofferdam slope protection 2-4 is flush with the top surface of the homogeneous soil filling material 2-3, and the bottom is 1m below the lowest water level upstream of the cofferdam.

[0069] The cofferdam slope protection 2-4 adopts the form of geotextile plus block stone weighting. After the cofferdam earth filling and slope repair are completed, a layer of geotextile is laid first, with a specification of not less than 300g / ㎡, which mainly plays the role of anti-filtration to prevent the loss of cofferdam soil. Then a layer of block stone slope protection is laid, and the thickness of the block stone layer is not less than 0.3m.

[0070] The anti-seepage curtain 8 is formed by grouting along the dam axis of the dam foundation 12, and its main function is to prevent leakage from the dam foundation. The top of the anti-seepage curtain 8 is connected to the downstream end of the lower composite geomembrane 5-1 by a concrete block weight; the anti-seepage curtain 8 is arranged at the dam axis position at the bottom of the dam foundation, which can significantly shorten the anti-seepage curtain axis, reduce the curtain engineering workload, and facilitate the improvement of construction speed.

[0071] Continue reading Figure 1 The anti-seepage structure based on the permanent and temporary dispersed earth dam also includes a drainage anti-seepage layer, which is laid on the water-facing surface of the dispersed earth dam body 1, the back water surface of the retaining cofferdam 2, and the interlayer upstream of the dam axis of the dispersed earth dam body 1 and the dam foundation 12, and the drainage anti-seepage layer is connected to the anti-seepage curtain 8.

[0072] The anti-seepage structure based on the permanent and temporary combined dispersed earth dam also includes a transition layer 3, which is arranged between the drainage anti-seepage layer and the dispersed earth dam body 1, or in other words, the transition layer 3 is arranged on the upstream side and bottom of the dispersed earth dam body 1, mainly to isolate the dispersed soil from the seepage. The transition layer 3 uses non-dispersed soil or modified dispersed soil. The modified dispersed soil uses dispersed soil mixed with 1% to 4% slaked lime. The specific amount needs to be determined based on field tests. The thickness of the transition layer 3 should be 1.5m to 3.5m, with a smaller value for low dams and a larger value for high dams. The thickness should be appropriately thickened in areas with seismic intensity of VIII and IX or above. At the same time, the compaction degree meets the requirements of the "Design Code for Roller Compacted Earth-Rock Dams" (SL274-2020).

[0073] like Figure 1 As shown, the transition layer 3 covers the water-facing surface of the dispersed earth dam body 1 , the water-retaining surface of the water-retaining cofferdam 2 , and the dam base of the dam foundation 12 .

[0074] In addition to the above structures, the anti-seepage structure based on the permanent-temporary combined decentralized earth dam also includes a drainage prism 10, which is arranged at the downstream slope foot of the decentralized earth dam body 1. The drainage prism 10 can quickly discharge seepage water.

[0075] In some embodiments, the drainage prism 10 is filled with blocks of stone, the strength of the blocks of stone is not less than 30 MPa, the particle size is not greater than 40 cm, the top width of the drainage prism 10 is not less than 2 m, the upstream slope ratio is not steeper than 1:1, the downstream slope ratio is not steeper than 1:1.5, and the top elevation should be higher than the transition layer 3.

[0076] A support layer 11 is also arranged at the bottom of the dam foundation. At the same time, the support layer 11 is arranged upstream of the dam axis and located between the drainage and anti-seepage layer and the dam foundation 12. The support layer 11 is mainly used to support the lower composite geomembrane 5-1 and play a leveling role to facilitate the laying of the composite geomembrane.

[0077] In some embodiments, the support layer 11 is made of non-dispersible soil or modified dispersible soil, and the modified dispersible soil is made of dispersible soil mixed with 1% to 4% slaked lime, and the specific mixing amount needs to be determined according to field tests. The top surface of the support layer 11 should be slightly higher than the top surface of the gravel drainage layer 9-1 to facilitate the rapid drainage of seepage water.

[0078] The compaction degree of the supporting layer 11 meets the requirements of the "Design Code for Roller-Compacted Earth-Rock Dams" (SL274-2020).

[0079] See also Figure 1 The drainage and anti-seepage layer includes a geotechnical drainage layer 4, a lower composite geomembrane 5-1 and an upper composite geomembrane 5-2, and the specific structure is as follows:

[0080] (I) The geotextile drainage layer 4 is laid in three parts, which are laid between the transition layer 3 and the supporting layer 11, between the transition layer 3 and the back water surface of the water retaining cofferdam 2, and between the transition layer 3 and the front water surface of the dispersed earth dam body 1, and the joints of the three parts are paved seamlessly.

[0081] The geotextile drainage layer 4 is arranged in the upstream and bottom area of ​​the transition layer 3, specifically between the transition layer and the composite geomembrane, and its main function is to discharge a small amount of seepage water.

[0082] In some embodiments, the geotechnical drainage layer 4 uses a geomat, the main material of which is a polypropylene resin permeable mesh. The compressive strength of the geomat meets more than 1.25 times the pressure generated by the upper protective layer and the water pressure load, and is not less than 0.5MPa. The thickness of the geotechnical drainage layer 4 is preferably 10cm.

[0083] (II) The lower composite geomembrane 5 - 1 is arranged between the geodrainage layer 4 and the support layer 11 , and between the geodrainage layer 4 and the back surface of the water retaining cofferdam 2 .

[0084] The lower composite geomembrane 5-1 is arranged below the geodetic drainage layer 4, at the bottom of the dam foundation, upstream of the central axis, and in the backwater area of ​​the cofferdam, extending into the bottom of the foot guard wall 7 and extending more than 1m.

[0085] In some embodiments, the lower composite geomembrane 5-1 uses 2 cloths and 1 membrane, and the specifications are: the geomembrane is not less than 0.5mm, and the geotextile is not less than 300g / ㎡.

[0086] (III) The upper composite geomembrane 5 - 2 is arranged on the upstream slope of the geodetic drainage layer 4 .

[0087] The upper composite geomembrane 5-2 is arranged on the upstream slope of the geodrainage layer 4, extends into the bottom of the foot guard wall 7 and exceeds 1m, and is double-sided welded with the lower composite geomembrane 5-1 at the broken end.

[0088] In some embodiments, the upper composite geomembrane 5-2 uses 2 cloths and 1 membrane, and the specifications are: the geomembrane is not less than 0.5mm, and the geotextile is not less than 300g / ㎡.

[0089] A protective layer 6 is arranged on the upstream slope of the upper composite geomembrane 5-2. The protective layer 6 is mainly composed of a mortar cushion layer and a concrete slab. The thickness of the mortar cushion layer is not less than 3 cm and the strength is not less than 7.5 MPa. The thickness of the concrete slab is not less than 20 cm and the strength is not less than C25.

[0090] A foot tooth wall 7 is arranged on the back water side of the water retaining cofferdam 2 and close to its top surface. The foot tooth wall 7 is embedded in the interior of the water retaining cofferdam 2. The main function of the foot tooth wall 7 is to improve the anti-slip ability of the protective layer 6 and to facilitate the firm connection between the lower composite geomembrane 5-1 and the upper composite geomembrane 5-2 through ballasting.

[0091] Continue reading Figure 1 The anti-seepage structure based on permanent and temporary combined dispersed earth dam also includes:

[0092] (a) The lower filter layer 9-2 is laid downstream of the dam axis of the dam foundation 12.

[0093] The lower filter layer 9-2 can prevent the dam foundation soil from migrating to the gravel drainage layer and blocking the gravel drainage layer.

[0094] The lower filter layer 9-2 is made of medium-coarse sand or gravel with good quality and gradation.

[0095] (b) Gravel drainage layer 9-1, laid on the lower filter layer 9-2.

[0096] The gravel drainage layer 9-1 is arranged downstream of the dam axis at the dam base, and the upstream of the gravel drainage layer 9-1 is connected to the geotechnical drainage layer 4. The gravel drainage layer 9-1 mainly discharges the seepage water of the dam slope and dam base, and the layer thickness is not less than 0.5m.

[0097] The gravel of the gravel drainage layer 9-1 is required to be solid and well-graded, with a particle size of 0.5 to 5 cm.

[0098] (c) The upper filter layer 9-3 is laid on the gravel drainage layer 9-1.

[0099] The upper filter layer 9-3 can prevent the soil in the transition layer 3 from migrating to the gravel drainage layer and blocking the gravel drainage layer.

[0100] The upper filter layer 9-3 is made of medium-coarse sand or gravel with good quality and gradation.

[0101] The top surface of the support layer 11 is higher than the top surface of the gravel drainage layer 9 - 1 , and the gravel drainage layer 9 - 1 is connected to the geotextile drainage layer 4 .

[0102] Based on the anti-seepage structure of Yonglin combined with decentralized earth dam, the construction process is as follows:

[0103] Step 100, first construct the water retaining cofferdam 2.

[0104] Specifically, the diversion dike 2-1 is constructed first, and then the air-tight material 2-2 is filled, the cofferdam foundation downstream of the dike 2-1 is cleaned, and then the homogeneous soil filling material 2-3 is rolled in layers, and then the cofferdam slope protection 2-4 is constructed.

[0105] Step 200, the foundation of other areas of the dam are then cleared.

[0106] Step 300, then layer by layer rolling to construct the support layer 11, lay the lower composite geomembrane 5-1, and lay the lower section of the geodetic drainage layer 4 to the top elevation of the cofferdam.

[0107] Step 400, construct the anti-seepage curtain 8, and use concrete blocks to weight and connect the ends of the lower composite geomembrane 5-1.

[0108] Step 500, construct the lower filter layer 9-2, the gravel drainage layer 9-1, the upper filter layer 9-3, and the drainage prism 10 simultaneously from bottom to top, adopting flat construction and layered rolling to control the construction surface to be the same elevation.

[0109] Step 600, construct the transition layer 3 and the dispersed earth dam body 1 from bottom to top simultaneously, adopting flat construction and layered rolling to control the construction surface to be the same elevation.

[0110] Step 700, then groove the top of the cofferdam to construct the working surface of the foot guard wall 7.

[0111] Step 800, then lay the upper section of the geodrainage layer 4 to the dam top; then lay the upper composite geomembrane 5-2, and weld it to the lower composite geomembrane 5-1 on both sides in the upstream external area of ​​the toe wall 7; then construct the toe wall 7, and backfill and compact the fill to restore the cofferdam top.

[0112] Step 900, finally construct the protective layer 6.

[0113] Yonglin combines the anti-seepage structure of the dispersed earth dam and makes full use of the good anti-seepage performance and low cost of geomembrane to layout the anti-seepage system. Specifically, the geomembrane is arranged along the water-facing surface of the dam, the back water surface of the cofferdam, and the dam foundation in sequence, and connected with the curtain grouting at the dam axis position at the dam base. A geotechnical drainage layer is set downstream of the geomembrane and a protective layer is set upstream, so that the anti-seepage drainage system is perfect, coordinated with the deformation of the surrounding soil, and economical and low cost.

[0114] Those skilled in the art will appreciate that the above-mentioned embodiments are specific examples for implementing the present invention, and in actual applications, various changes may be made thereto in form and detail without departing from the spirit and scope of the present invention.

Claims

1. The anti-seepage structure based on permanent and temporary combined dispersed earth dam is characterized by: At least: Dam foundation (12); A dispersed earth dam body (1) is formed by filling dispersed soil on the dam foundation (12); A water retaining cofferdam (2) is arranged on the upstream side of the dispersed earth dam body (1); An anti-seepage curtain (8) is formed by grouting along the dam axis of the dam foundation (12); A drainage and anti-seepage layer is laid on the water-facing surface of the dispersed earth dam body (1), the water-retaining surface of the water retaining cofferdam (2), and between the dispersed earth dam body (1) and the upstream interlayer of the dam axis of the dam foundation (12), and the drainage and anti-seepage layer is connected to the anti-seepage curtain (8); A transition layer (3) is arranged between the drainage and anti-seepage layer and the dispersed earth dam body (1).

2. The anti-seepage structure based on the permanent and temporary combined dispersed earth dam according to claim 1 is characterized in that: Also includes: The drainage prism (10) is arranged at the downstream slope foot of the dispersed earth dam body (1).

3. The anti-seepage structure based on the permanent and temporary combined dispersed earth dam according to claim 1 or 2 is characterized in that: Also includes: The support layer (11) is arranged upstream of the dam axis and is located between the drainage and anti-seepage layer and the dam foundation (12).

4. The anti-seepage structure based on the permanent and temporary combined dispersed earth dam according to claim 3 is characterized in that: The drainage and anti-seepage layer comprises: The geotextile drainage layer (4) is laid in three parts, which are laid respectively between the transition layer (3) and the support layer (11), between the transition layer (3) and the back water surface of the water retaining cofferdam (2), and between the transition layer (3) and the front water surface of the dam body (1) of the dispersed earth dam, and the joints of the three parts are laid seamlessly; A lower composite geomembrane (5-1) is arranged between the geotechnical drainage layer (4) and the support layer (11), and between the geotechnical drainage layer (4) and the back water surface of the water retaining cofferdam (2); The upper composite geomembrane (5-2) is arranged on the upstream slope of the geotechnical drainage layer (4).

5. The anti-seepage structure based on the permanent and temporary combined dispersed earth dam according to claim 4 is characterized in that: Also includes: A protective layer (6) is arranged on the upstream slope of the upper composite geomembrane (5-2); The protective layer (6) consists of a mortar cushion layer and a concrete slab.

6. The anti-seepage structure based on the permanent and temporary combined dispersed earth dam according to claim 5 is characterized in that: Also includes: A foot protection tooth wall (7) is arranged on the back surface of the water retaining cofferdam (2) and close to the top surface; The foot guard tooth wall (7) is embedded in the interior of the water retaining cofferdam (2).

7. The anti-seepage structure based on the permanent and temporary combined dispersed earth dam according to claim 5 is characterized in that: The transition layer (3) covers the water-facing surface of the dispersed earth dam body (1), the water-retaining surface of the water-retaining cofferdam (2), and the dam base of the dam foundation (12).

8. The anti-seepage structure based on the permanent and temporary combined dispersed earth dam according to claim 7 is characterized in that: Also includes: A lower filter layer (9-2) is laid downstream of the dam axis of the dam foundation (12); A crushed stone drainage layer (9-1) is laid on the lower filter layer (9-2); An upper filter layer (9-3) is laid on the gravel drainage layer (9-1); The top surface of the support layer (11) is higher than the top surface of the gravel drainage layer (9-1), and the gravel drainage layer (9-1) is connected to the geotechnical drainage layer (4).

9. The anti-seepage structure based on the permanent and temporary combined dispersed earth dam according to claim 1 is characterized in that: The water retaining cofferdam (2) is arranged in steps, comprising: A dike (2-1) is arranged on the upstream side of the dispersed earth dam body (1); The air-tight material (2-2) is arranged on the upstream side of the dike (2-1); Homogeneous soil filler (2-3), arranged on the downstream side of the dike (2-1); The top surfaces of the airtight material (2-2), the dike (2-1), and the homogeneous soil filler (2-3) gradually rise to form three steps, and a cofferdam slope protection (2-4) is laid on the top surfaces of the three. The top surface of the cofferdam slope protection (2-4) is flush with the top surface of the homogeneous soil filler (2-3).

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